'[Weathertop] is a hill, just to the north of the Old Road, about half way from [Bree] to Rivendell. It commands a wide view all round....'

The Fellowship of the Ring, LoTR Book 1, Ch 10, Strider

Away in the distance eastward they could now see a line of hills. The highest of them was at the right of the line and a little separated from the others. It had a conical top, slightly flattened at the summit.

'That is Weathertop,' said Strider. 'The Old Road, which we have left far away on our right, runs to the south of it and passes not far from its foot.'

The Fellowship of the Ring, LoTR Book 1, Ch 11, A Knife in the Dark

It was already mid-day when they drew near ... a grey-green bank, leading up like a bridge on to the northward slope of the hill. ...

On the western flank of Weathertop they found a sheltered hollow, at the bottom of which there was a bowl-shaped dell with grassy sides. ... After half an hour's plodding climb Strider reached the crown of the hill.... The last slope had been steep and rocky.

On the top they found ... a wide ring of ancient stonework, now crumbling or covered with age-long grass. ...

Standing upon the rim of the ruined circle, they saw all round below them a wide prospect, for the most part of lands empty and featureless, except for patches of woodland away to the south, beyond which they caught here and there the glint of distant water. Beneath them on this southern side there ran like a ribbon the Old Road, coming out of the West and winding up and down, until it faded behind a ridge of dark land to the east. ... Following its line eastward with their eyes they saw the Mountains: the nearer foothills were brown and sombre; behind them stood taller shapes of grey, and behind those again were high white peaks glimmering among the clouds.

'Well, here we are!' said Merry. 'And very cheerless and uninviting it looks! There is no water and no shelter.'

[Answered] Strider[,] ... 'I know how long it would take me on my own feet, with fair weather and no ill fortune: twelve days from here to the Ford of Bruinen....'

The Fellowship of the Ring, LoTR Book 1, Ch 11, A Knife in the Dark

'The Men of the West did not live here.... But..., in the first days of the North Kingdom, they built a great watch-tower on Weathertop, Amon Sûl they called it. It was burned and broken, and nothing remains of it now but a tumbled ring, like a rough crown on the old hill's head. Yet once it was tall and fair. It is told that Elendil stood there watching for the coming of Gil-galad out of the West, in the days of the Last Alliance.'

All the kingdoms met at Weathertop, and the desire to obtain that frontier fortress ... caused further enmity between the realms....

The Atlas of Middle-earth, Revised Edition, by Karen Wynn Fonstad, Section 3, The Third Age: Kingdoms of the Dúnedain

There was often strife between the kingdoms.... The chief matter of debate was the possession of the Weather Hills and the land westward towards Bree. Both Rhudaur and Cardolan desired to possess Amon Sûl (Weathertop), which stood on the borders of their realms; for the Tower of Amon Sûl held the chief Palantír of the North, and the other two were both in the keeping of Arthedain.

The Return of the King, LoTR Appendix A, Annals of the Kings and Rulers: Eriador, Arnor, and the Heirs of Isildur: The North-kingdom and the Dúnedain

A great host came out of Angmar in 1409, and crossing the river entered Cardolan and surrounded Weathertop. The Dúnedain were defeated.... The Tower of Amon Sûl was burned and razed; but the palantír was saved and carried back in retreat to Fornost.

The Return of the King, LoTR Appendix A, Annals of the Kings and Rulers: Eriador, Arnor, and the Heirs of Isildur: The North-kingdom and the Dúnedain